How about a SIG 716? I previously owned a Bushmaster LR308 MOE 16" mid length carbine and the fit and finish on the SIG is far better.

In reality, the long action ARs are pretty impractical in the carbine format as you get all the extra weight of the platform coupled with the loss in velocity of a shorter barrel. If you must own the platform in 308 buy a full length precision gun as the 16" version really doesn't have any advantages over the 5.56.